A compact fluorescent lamp (CFL) is widely used for lighting. A conventional CFL includes a light tube, having a phosphor coating on its inner surface, and containing an inert gas and mercury substance, where the mercury is in the form of mercury vapor or liquid mercury. The light tube is enclosed with caps at its two ends, at which a cathode and anode are disposed therein. When enough electric voltage is applied to the cathode and anode, the cathode emits electrons and causes the mercury to discharge, thereby conducting the electric current to the anode. In the course of discharge, the mercury emits ultraviolet rays that excite the phosphor coating to generate visible light. The cathode is usually shaped as a wire having a diameter of about one millimeter. In order to electrically excite the mercury to emit ultraviolet rays, the cathode is usually required to operate at a temperature approximating 800 degrees Celsius.
A cold cathode fluorescent lamp (CCFL) has a basic structure similar to CFL in the sense that they all need a light tube with a phosphor coated inner layer that contains an inert gas, a mercury substance, and a cathode electrically connected to a power source for exciting the mercury. The CCFL differs from the CFL in the sense that the cathode of the CCFL has a larger surface area and a lower functioning temperature. The cathode of the CCFL is usually shaped as a single or multiple layers of plates, such that its surface area is larger than the wire-shaped cathode of a CFL. Additionally, only a temperature about 100 degrees Celsius is required for the cathode of a CCFL to function. Thus the name “cold cathode” is given to the CCFL when comparing it to the traditional cathode fluorescent lamp.
Because the cold cathode functions at a lower temperature, the life span of the CCFL usually lasts longer than its comparative models of CFL. Moreover, the CCFL can better survive an impact force than does the CFL, because it is easier for the impact force to disconnect the wire-shaped cathode of CFL from the power source than to disconnect the plate shaped cathode from the same.
The following prior art discloses the various aspects in the design of spirally shaped cold cathode fluoresent lamps.
U.S. Pat. No. 5,256,935, granted Oct. 26, 1993, to Y. Dobashi et al., discloses a cold cathode mercury vapor discharge lamp that includes a bulb, a support wire within the bulb, and a cathode electrode having a pair of V-shaped electrode portions mounted in spaced, end to end relationship along the support wire. The electrodes include exterior surfaces facing towards the bulb walls, and interior surfaces facing towards the support wire. Getters are mounted on the exterior surfaces, and mercury discharge units are mounted on the interior surfaces. The two electrode portions are non-overlapping along the support wire.
U.S. Pat. No. 6,064,155, granted May 16, 2000, to J. Maya, et al., discloses a compact fluorescent lamp that is designed to imitate an incandescent lamp in size, shape and luminosity. The lamp includes a bulbous envelope having an external shape of an incandescent lamp on a standard Edison-type base that enables it to be substituted for standard 60, 75 and 100 W. incandescent lamps. A low-pressure fluorescent lamp having a coiled tubular envelope with an outer diameter less than about 7 mm., an inner diameter between about 1 and 7 mm, and a length between about 50 and 100 cm. is wound in a coil around the axis of the bulbous envelope and is disposed within the bulbous envelope. The tubular envelope is formed of soft glass and has a fluorescent phosphor coating disposed on the inner surfaces. Electrodes with external electrical contacts are disposed at each end of the envelope. A ballast is disposed within the bulbous envelope. The ballast is electrically connected to the lamp, whereby to control current in the fluorescent lamp. A heat shield is disposed between the lamp and the ballast to thermally isolate the lamp from the ballast, whereby heat from the lamp will not adversely affect the ballast.
U.S. Pat. No. 6,515,433, granted Feb. 4, 2003, to S. Ge, et al., discloses where the sputtering of the cathodes of a cold cathode fluorescent lamp is reduced or eliminated by removing electrodes altogether from the sealed envelope containing the gaseous medium. Electric field is then applied by means of electrically conductive members outside the tube. Alternatively, the current passing between electrodes can be spread over multiple sub-electrodes so that the current flow and sputtering experienced by each individual sub-electrode will be reduced. Different designs are employed to facilitate heat dissipation for high power and high intensity cold cathode fluorescent lamp applications. Thus, a container for the fluorescent lamp tube may be omitted altogether and adjacent rounds of a spiral-shaped lamp may be attached together by an adhesive material. Alternatively, the container may be open at one end to facilitate heat dissipation. Or the container for the lamp and the housing from the driver tray each contain a hole to allow air circulation to carry away heat.
U.S. Pat. No. 6,646,365, granted Nov. 11, 2003, to C. J. M. Denissen, et al., teaches of a low-pressure mercury-vapor discharge lamp that has a discharge vessel filled with mercury and an inert gas. Electrodes in the discharge space have electrode shields, which operate at temperatures above 450° C. An inner surface of the electrode shield may have a heat-absorbing coating, for example a carbon film. The electrode shield may be supported by a support wire, at least a part of which is made from stainless steel. A lamp according to the invention has comparatively low mercury consumption.
Therefore, what is needed is a CCFL containing a gas absorbing alloy in its light tube that has an improved capability of absorbing oxygenic gas which can result in a lower operating temperature that will increase the life span of the cathode of a CCFL.
It is therefore an object of the present invention is to provide a light tube for a cold cathode fluorescent lamp that includes a zirconium-aluminum-based gas absorber, which is able to be activated at an activation temperature substantially lower than 900 degrees Celsius and has better efficiency of gas absorption than conventional ones.
It is another object of the present invention to provide a light tube for a cold cathode fluorescent lamp that includes a zirconium-aluminum based gas absorber, which is able to be activated at an activation temperature about 390 degrees Celsius, that is during the general gas discharging step of its manufacturing process, so as to minimize its manufacturing processes and cost and to eliminate those expensive heating equipments
It is still another object of the present invention to provide a light tube for a cold cathode fluorescent lamp whose cathode is made in various shapes for enlarging a surface area of the cathode in order to enhance the cathode in terms of resisting oxidation and surviving an impact force applied to the light tube.
It is still yet another object of the present invention to provide a light tube for a cold cathode fluorescent lamp that is made in various shapes in order to reduce a space occupied by the same.
It is yet still another object of the present invention to provide a cold cathode fluorescent lamp that includes a housing air-tightly attached to an igniter casing extended from a base for maintaining heat therein in order to warm the cathode.
An additional object of the present invention is to provide a cold cathode fluorescent lamp that includes a housing attached to an igniter casing extended from a base, wherein an air passage is formed between the housing and the igniter casing for balancing pressure within and without the housing.
Yet, another object of the present invention is to provide a cold cathode fluorescent lamp that includes an igniter for driving the cold cathode to a functioning stage.
A final object of the present invention is to provide a cold cathode fluorescent lamp that includes a housing envelope made of colors for effects of colorful illumination.
In order to accomplish the above objectives, the present invention provides a light tube for a cold cathode fluorescent lamp comprising: a light tube body, having a first end portion and second end portion, containing an inert gas, a mercury substance and a phosphor coating layer on an inner surface of the light tube body; an anode, disposed at the first end portion in the light tube body, is adapted for connecting to a positive terminal of electricity; a cathode, disposed at the second end portion in the light tube body, is adapted for electrically connecting to the negative terminal for emitting electrons to excite the mercury substance for conducting the electrons to the anode as a electric loop, wherein the excited mercury substance emits ultra violet rays causing the phosphor coating to generate visible light; and a gas absorber, made of zirconium-aluminum alloy, formed at the cathode for absorbing oxygenic gas.
These and other objects, features, and advantages of the present invention will become apparent from reading the following detailed description, the accompanying drawings, and the appended claims.